fix: preserve the dollar escaping semantics of godotenv

Also removes _any_ source data from showing from config errors.

Author: Chris Stockton

internal/conf/envparse/envparse.go

@@ -34,7 +34,6 @@ package envparse
 import (
 	"bytes"
 	"errors"
-	"fmt"
 	"io"
 	"strings"
 	"unicode"
@@ -158,10 +157,7 @@ loop:
 			if unicode.IsLetter(rchar) || unicode.IsNumber(rchar) || rchar == '.' {
 				continue
 			}
-
-			return "", nil, fmt.Errorf(
-				`unexpected character %q in variable name near %q`,
-				string(char), string(src))
+			return "", nil, errors.New("unexpected character in variable name")
 		}
 	}
 
@@ -175,6 +171,26 @@ loop:
 	return key, cutset, nil
 }
 
+// expandDollarEscapes preserves godotenvs dollar escaping.
+func expandDollarEscapes(src []byte) []byte {
+	var n int
+	for r := 0; r < len(src); r++ {
+		if src[r] != '$' {
+			src[n] = src[r]
+			n++
+			continue
+		}
+
+		if n > 0 && src[n-1] == '\\' {
+			n--
+		}
+
+		src[n] = '$'
+		n++
+	}
+	return src[:n]
+}
+
 // extractVarValue extracts variable value and returns rest of slice.
 func extractVarValue(src []byte) (value string, rest []byte, err error) {
 	quote, hasPrefix := hasQuotePrefix(src)
@@ -211,8 +227,8 @@ func extractVarValue(src []byte) (value string, rest []byte, err error) {
 			}
 		}
 
-		trimmed := strings.TrimFunc(string(line[0:endOfVar]), isSpace)
-		return trimmed, src[endOfLine:], nil
+		trimmed := []byte(strings.TrimFunc(string(line[0:endOfVar]), isSpace))
+		return string(expandDollarEscapes(trimmed)), src[endOfLine:], nil
 	}
 
 	// lookup quoted string terminator
@@ -227,6 +243,7 @@ func extractVarValue(src []byte) (value string, rest []byte, err error) {
 		valueBytes := src[1:i]
 		if quote == prefixDoubleQuote {
 			valueBytes = expandEscapes(valueBytes)
+			valueBytes = expandDollarEscapes(valueBytes)
 		}
 
 		value = string(valueBytes)
@@ -238,7 +255,7 @@ func extractVarValue(src []byte) (value string, rest []byte, err error) {
 	if valEndIndex == -1 {
 		valEndIndex = len(src)
 	}
-	return "", nil, fmt.Errorf("unterminated quoted value %s", src[:valEndIndex])
+	return "", nil, errors.New("unterminated quoted value")
 }
 
 func isEscaped(src []byte, index int) bool {

internal/conf/envparse/envparse_test.go

@@ -9,11 +9,11 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func TestParseCompatibility(t *testing.T) {
-	join := func(s ...string) []byte {
-		return []byte(strings.Join(s, "\n"))
-	}
+func join(s ...string) []byte {
+	return []byte(strings.Join(s, "\n"))
+}
 
+func TestParseCompatibility(t *testing.T) {
 	type testCase struct {
 		name   string
 		from   []byte
@@ -35,6 +35,16 @@ func TestParseCompatibility(t *testing.T) {
 			from: []byte("FOO=#bar"),
 			exp:  map[string]string{"FOO": "#bar"},
 		},
+		{
+			name:   "unterminated squote value",
+			from:   []byte(`FOO='bar`),
+			errStr: "unterminated quoted value",
+		},
+		{
+			name:   "unterminated dquote value",
+			from:   []byte(`FOO="bar`),
+			errStr: "unterminated quoted value",
+		},
 
 		// godot - TestParse
 		{
@@ -113,7 +123,7 @@ func TestParseCompatibility(t *testing.T) {
 				`INVALID LINE`,
 				`foo=bar`,
 			),
-			errStr: `unexpected character "\n" in variable name near "INVALID LINE\nfoo=bar"`,
+			errStr: `unexpected character`,
 		},
 		{
 			name: "godot - fixtures/plain.env",
@@ -449,6 +459,7 @@ func TestParseCompatibility(t *testing.T) {
 
 	runParseTest := func(t *testing.T, tt testCase) {
 		check := func(t *testing.T, exp, got map[string]string, err error) {
+			t.Helper()
 			if tt.errStr != "" {
 				require.Error(t, err)
 				require.Contains(t, err.Error(), tt.errStr)